Fix Permissions Reference for getForbiddenPlmns()

Previously this was incorrectly using an internal-only permission
for a public API. Need to use the external version.

Bug: 35261110
Test: TelephonyManagerTest.testGetForbiddenPlmns
Merged-In: Ia4bb90a4cad92f61781128a0a381e2ad087b07e1
Change-Id: Ia4bb90a4cad92f61781128a0a381e2ad087b07e1
(cherry picked from commit 892104e2929f221f87f8e30c446f381a9ea2f0b8)
1 file changed